DOCUMENT:Q188341  05-AUG-1999  [exchange]
TITLE   :XFOR: AUTH/EHLO Commands Cause Internet Mail Service to Stop
PRODUCT :Microsoft Exchange
PROD/VER:winnt:5.0,5.5
OPER/SYS:
KEYWORDS:exc5 exc55

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The information in this article applies to:

 - Microsoft Exchange Server, versions 5.0, 5.5 
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SYMPTOMS
========

A malicious attacker might connect to the SMTP port of an Microsoft Exchange
Server 5.0 or 5.5 computer and disrupt the Internet Mail Service by issuing
specific sequences of AUTH or XAUTH commands. When this occurs, the following
error message may be displayed:

   msexcimc.exe - Application Error

   The instruction at "0x77f7d514" reference memory at "0x711cc771". The memory
   could not be written.

CAUSE
=====

Improper checking of bounds conditions on certain AUTH or XAUTH command
sequences may result in a buffer overflow.


STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 5.0.

A supported fix is now available, but has not been fully regression-tested and
should be applied only to systems experiencing this specific problem. Unless you
are severely impacted by this specific problem, Microsoft recommends that you
wait for the next service pack that contains this fix. Contact Microsoft
Technical Support for more information.

This fix has been posted to the following Internet location:

   ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/Eng/Exchg5.0/Post-SP2-IMS/




Microsoft has confirmed this to be a problem in Microsoft Exchange Server version
5.5. This problem has been corrected in the latest U.S. service pack for
Microsoft Exchange Server version 5.5. For information on obtaining the service
pack, query on the following word in the Microsoft Knowledge Base (without the
spaces):

   S E R V P A C K



Additional query words: base64 extended hello helo ims connector imc

======================================================================
Keywords          : exc5 exc55 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbZNotKeyword2
Version           : winnt:5.0,5.5
Issue type        : kbbug
Solution Type     : kbfix

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